Table 3.

Legionella culturing and monoclonal antibody testing of potable water samples collected from an apartment complex for seniors (n = 103 samples)

Sample site	No. tested	No. (%) positive
		Any Legionella*	L. pneumophila 1 (1,2,3)**
Affected buildings (A-1 and A-2)†
Water intake valves	11	6 (55%)	0
A-1 apartments	21	21 (100%)	18 (86%)
A-2 apartments	21	20 (95%)	13 (62%)
Common areas	22	12 (55%)	0
Unaffected buildings (U-1 and U-2)†
Water intake valves	8	1 (13%)	0
U-1 apartments	7	4 (57%)	0
U-2 apartments	7	6 (86%)	0
Fire hydrants	6	2 (33%)	0

* Any Legionella includes L. pneumophila and other undetermined species of blue-white Legionella that typically are not pathogenic.

**L. pneumophila 1 (1,2,3) denotes serogroup 1, monoclonal antibody type Knoxville (1,2,3).

^† Cases occurred among residents and visitors of affected buildings A-1 and A-2 only.